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<title>The decorators Example: Decorating a Bean - The Java EE 6 Tutorial</title>
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      <td width="400px"><p class="toc level1"><a href="docinfo.html">Document Information</a></p>
<p class="toc level1 tocsp"><a href="gexaf.html">Preface</a></p>
<p class="toc level1 tocsp"><a href="gfirp.html">Part&nbsp;I&nbsp;Introduction</a></p>
<p class="toc level2"><a href="bnaaw.html">1.&nbsp;&nbsp;Overview</a></p>
<p class="toc level2"><a href="gfiud.html">2.&nbsp;&nbsp;Using the Tutorial Examples</a></p>
<p class="toc level1 tocsp"><a href="bnadp.html">Part&nbsp;II&nbsp;The Web Tier</a></p>
<p class="toc level2"><a href="bnadr.html">3.&nbsp;&nbsp;Getting Started with Web Applications</a></p>
<p class="toc level2"><a href="bnaph.html">4.&nbsp;&nbsp;JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="giepx.html">5.&nbsp;&nbsp;Introduction to Facelets</a></p>
<p class="toc level2"><a href="gjddd.html">6.&nbsp;&nbsp;Expression Language</a></p>
<p class="toc level2"><a href="bnaqz.html">7.&nbsp;&nbsp;Using JavaServer Faces Technology in Web Pages</a></p>
<p class="toc level2"><a href="gjcut.html">8.&nbsp;&nbsp;Using Converters, Listeners, and Validators</a></p>
<p class="toc level2"><a href="bnatx.html">9.&nbsp;&nbsp;Developing with JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="gkmaa.html">10.&nbsp;&nbsp;JavaServer Faces Technology Advanced Concepts</a></p>
<p class="toc level2"><a href="bnawo.html">11.&nbsp;&nbsp;Configuring JavaServer Faces Applications</a></p>
<p class="toc level2"><a href="gkiow.html">12.&nbsp;&nbsp;Using Ajax with JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="gkhxa.html">13.&nbsp;&nbsp;Advanced Composite Components</a></p>
<p class="toc level2"><a href="bnavg.html">14.&nbsp;&nbsp;Creating Custom UI Components</a></p>
<p class="toc level2"><a href="bnafd.html">15.&nbsp;&nbsp;Java Servlet Technology</a></p>
<p class="toc level2"><a href="bnaxu.html">16.&nbsp;&nbsp;Internationalizing and Localizing Web Applications</a></p>
<p class="toc level1 tocsp"><a href="bnayk.html">Part&nbsp;III&nbsp;Web Services</a></p>
<p class="toc level2"><a href="gijti.html">17.&nbsp;&nbsp;Introduction to Web Services</a></p>
<p class="toc level2"><a href="bnayl.html">18.&nbsp;&nbsp;Building Web Services with JAX-WS</a></p>
<p class="toc level2"><a href="giepu.html">19.&nbsp;&nbsp;Building RESTful Web Services with JAX-RS</a></p>
<p class="toc level2"><a href="gjjxe.html">20.&nbsp;&nbsp;Advanced JAX-RS Features</a></p>
<p class="toc level2"><a href="gkojl.html">21.&nbsp;&nbsp;Running the Advanced JAX-RS Example Application</a></p>
<p class="toc level1 tocsp"><a href="bnblr.html">Part&nbsp;IV&nbsp;Enterprise Beans</a></p>
<p class="toc level2"><a href="gijsz.html">22.&nbsp;&nbsp;Enterprise Beans</a></p>
<p class="toc level2"><a href="gijre.html">23.&nbsp;&nbsp;Getting Started with Enterprise Beans</a></p>
<p class="toc level2"><a href="gijrb.html">24.&nbsp;&nbsp;Running the Enterprise Bean Examples</a></p>
<p class="toc level2"><a href="bnbpk.html">25.&nbsp;&nbsp;A Message-Driven Bean Example</a></p>
<p class="toc level2"><a href="gkcqz.html">26.&nbsp;&nbsp;Using the Embedded Enterprise Bean Container</a></p>
<p class="toc level2"><a href="gkidz.html">27.&nbsp;&nbsp;Using Asynchronous Method Invocation in Session Beans</a></p>
<p class="toc level1 tocsp"><a href="gjbnr.html">Part&nbsp;V&nbsp;Contexts and Dependency Injection for the Java EE Platform</a></p>
<p class="toc level2"><a href="giwhb.html">28.&nbsp;&nbsp;Introduction to Contexts and Dependency Injection for the Java EE Platform</a></p>
<p class="toc level2"><a href="gjbls.html">29.&nbsp;&nbsp;Running the Basic Contexts and Dependency Injection Examples</a></p>
<p class="toc level2"><a href="gjehi.html">30.&nbsp;&nbsp;Contexts and Dependency Injection for the Java EE Platform: Advanced Topics</a></p>
<p class="toc level2"><a href="gkhre.html">31.&nbsp;&nbsp;Running the Advanced Contexts and Dependency Injection Examples</a></p>
<p class="toc level3"><a href="gkhpu.html">The <tt>encoder</tt> Example: Using Alternatives</a></p>
<p class="toc level4"><a href="gkhpu.html#gkhqa">The <tt>Coder</tt> Interface and Implementations</a></p>
<p class="toc level4"><a href="gkhpu.html#gkhpm">The <tt>encoder</tt> Facelets Page and Managed Bean</a></p>
<p class="toc level4"><a href="gkhpu.html#gkhqq">Building, Packaging, Deploying, and Running the <tt>encoder</tt> Example</a></p>
<p class="toc level5"><a href="gkhpu.html#gkhow">To Build, Package, and Deploy the <tt>encoder</tt> Example Using NetBeans IDE</a></p>
<p class="toc level5"><a href="gkhpu.html#gkhqu">To Run the <tt>encoder</tt> Example Using NetBeans IDE</a></p>
<p class="toc level5"><a href="gkhpu.html#gkhql">To Build, Package, and Deploy the <tt>encoder</tt> Example Using Ant</a></p>
<p class="toc level5"><a href="gkhpu.html#gkhol">To Run the <tt>encoder</tt> Example Using Ant</a></p>
<p class="toc level3 tocsp"><a href="gkhpy.html">The <tt>producermethods</tt> Example: Using a Producer Method To Choose a Bean Implementation</a></p>
<p class="toc level4"><a href="gkhpy.html#gkhro">Components of the <tt>producermethods</tt> Example</a></p>
<p class="toc level4"><a href="gkhpy.html#gkhqe">Building, Packaging, Deploying, and Running the <tt>producermethods</tt> Example</a></p>
<p class="toc level5"><a href="gkhpy.html#gkhpe">To Build, Package, and Deploy the <tt>producermethods</tt> Example Using NetBeans IDE</a></p>
<p class="toc level5"><a href="gkhpy.html#gkhps">To Build, Package, and Deploy the <tt>producermethods</tt> Example Using Ant</a></p>
<p class="toc level5"><a href="gkhpy.html#gkhqg">To Run the <tt>producermethods</tt> Example</a></p>
<p class="toc level3 tocsp"><a href="gkhrg.html">The <tt>producerfields</tt> Example: Using Producer Fields to Generate Resources</a></p>
<p class="toc level4"><a href="gkhrg.html#gkhpp">The Producer Field for the <tt>producerfields</tt> Example</a></p>
<p class="toc level4"><a href="gkhrg.html#gkhpd">The <tt>producerfields</tt> Entity and Session Bean</a></p>
<p class="toc level4"><a href="gkhrg.html#gkhpf">The <tt>producerfields</tt> Facelets Pages and Managed Bean</a></p>
<p class="toc level4"><a href="gkhrg.html#gkhrh">Building, Packaging, Deploying, and Running the <tt>producerfields</tt> Example</a></p>
<p class="toc level5"><a href="gkhrg.html#gkhpb">To Build, Package, and Deploy the <tt>producerfields</tt> Example Using NetBeans IDE</a></p>
<p class="toc level5"><a href="gkhrg.html#gkhrm">To Build, Package, and Deploy the <tt>producerfields</tt> Example Using Ant</a></p>
<p class="toc level5"><a href="gkhrg.html#gkhrr">To Run the <tt>producerfields</tt> Example</a></p>
<p class="toc level3 tocsp"><a href="gkhpa.html">The <tt>billpayment</tt> Example: Using Events and Interceptors</a></p>
<p class="toc level4"><a href="gkhpa.html#gkhok">The <tt>PaymentEvent</tt> Event Class</a></p>
<p class="toc level4"><a href="gkhpa.html#gkhrb">The <tt>PaymentHandler</tt> Event Listener</a></p>
<p class="toc level4"><a href="gkhpa.html#gkhrj">The <tt>billpayment</tt> Facelets Pages and Managed Bean</a></p>
<p class="toc level4"><a href="gkhpa.html#gkhrq">The <tt>LoggedInterceptor</tt> Interceptor Class</a></p>
<p class="toc level4"><a href="gkhpa.html#gkhpk">Building, Packaging, Deploying, and Running the <tt>billpayment</tt> Example</a></p>
<p class="toc level5"><a href="gkhpa.html#gkhqs">To Build, Package, and Deploy the <tt>billpayment</tt> Example Using NetBeans IDE</a></p>
<p class="toc level5"><a href="gkhpa.html#gkhpx">To Build, Package, and Deploy the <tt>billpayment</tt> Example Using Ant</a></p>
<p class="toc level5"><a href="gkhpa.html#gkhpt">To Run the <tt>billpayment</tt> Example</a></p>
<div id="scrolltoc" class="onpage">
<p class="toc level3 tocsp"><a href="">The <tt>decorators</tt> Example: Decorating a Bean</a></p>
<p class="toc level4"><a href="#gkpaq">Components of the <tt>decorators</tt> Example</a></p>
<p class="toc level4"><a href="#gkpbk">Building, Packaging, Deploying, and Running the <tt>decorators</tt> Example</a></p>
<p class="toc level5"><a href="#gkpag">To Build, Package, and Deploy the <tt>decorators</tt> Example Using NetBeans IDE</a></p>
<p class="toc level5"><a href="#gkpaj">To Build, Package, and Deploy the <tt>decorators</tt> Example Using Ant</a></p>
<p class="toc level5"><a href="#gkpan">To Run the <tt>decorators</tt> Example</a></p>
</div>
<p class="toc level1 tocsp"><a href="bnbpy.html">Part&nbsp;VI&nbsp;Persistence</a></p>
<p class="toc level2"><a href="bnbpz.html">32.&nbsp;&nbsp;Introduction to the Java Persistence API</a></p>
<p class="toc level2"><a href="gijst.html">33.&nbsp;&nbsp;Running the Persistence Examples</a></p>
<p class="toc level2"><a href="bnbtg.html">34.&nbsp;&nbsp;The Java Persistence Query Language</a></p>
<p class="toc level2"><a href="gjitv.html">35.&nbsp;&nbsp;Using the Criteria API to Create Queries</a></p>
<p class="toc level2"><a href="gkjiq.html">36.&nbsp;&nbsp;Creating and Using String-Based Criteria Queries</a></p>
<p class="toc level2"><a href="gkjjf.html">37.&nbsp;&nbsp;Controlling Concurrent Access to Entity Data with Locking</a></p>
<p class="toc level2"><a href="gkjia.html">38.&nbsp;&nbsp;Improving the Performance of Java Persistence API Applications By Setting a Second-Level Cache</a></p>
<p class="toc level1 tocsp"><a href="gijrp.html">Part&nbsp;VII&nbsp;Security</a></p>
<p class="toc level2"><a href="bnbwj.html">39.&nbsp;&nbsp;Introduction to Security in the Java EE Platform</a></p>
<p class="toc level2"><a href="bncas.html">40.&nbsp;&nbsp;Getting Started Securing Web Applications</a></p>
<p class="toc level2"><a href="bnbyk.html">41.&nbsp;&nbsp;Getting Started Securing Enterprise Applications</a></p>
<p class="toc level1 tocsp"><a href="gijue.html">Part&nbsp;VIII&nbsp;Java EE Supporting Technologies</a></p>
<p class="toc level2"><a href="gijto.html">42.&nbsp;&nbsp;Introduction to Java EE Supporting Technologies</a></p>
<p class="toc level2"><a href="bncih.html">43.&nbsp;&nbsp;Transactions</a></p>
<p class="toc level2"><a href="bncjh.html">44.&nbsp;&nbsp;Resource Connections</a></p>
<p class="toc level2"><a href="bncdq.html">45.&nbsp;&nbsp;Java Message Service Concepts</a></p>
<p class="toc level2"><a href="bncgv.html">46.&nbsp;&nbsp;Java Message Service Examples</a></p>
<p class="toc level2"><a href="gkahp.html">47.&nbsp;&nbsp;Advanced Bean Validation Concepts and Examples</a></p>
<p class="toc level2"><a href="gkeed.html">48.&nbsp;&nbsp;Using Java EE Interceptors</a></p>
<p class="toc level1 tocsp"><a href="gkgjw.html">Part&nbsp;IX&nbsp;Case Studies</a></p>
<p class="toc level2"><a href="gkaee.html">49.&nbsp;&nbsp;Duke's Tutoring Case Study Example</a></p>
<p class="toc level1 tocsp"><a href="idx-1.html">Index</a></p>
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<a name="gkpax"></a><h2>The <tt>decorators</tt> Example: Decorating a Bean</h2>
<a name="indexterm-1590"></a><p>The <tt>decorators</tt> example, which is yet another variation on the <tt>encoder</tt> example, shows
how to use a decorator to implement additional business logic for a bean.
Instead of having the user choose between two alternative implementations of an interface
at deployment time or runtime, a decorator adds some additional logic to a
single implementation of the interface.</p>

<p>The example includes an interface, an implementation of it, a decorator, an interceptor,
a managed bean, a Facelets page, and configuration files.</p>



<a name="gkpaq"></a><h3>Components of the <tt>decorators</tt> Example</h3>
<p>The <tt>decorators</tt> example is very similar to the <tt>encoder</tt> example described in
<a href="gkhpu.html">The <tt>encoder</tt> Example: Using Alternatives</a>. Instead of providing two implementations of the <tt>Coder</tt> interface, however, this
example provides only the <tt>CoderImpl</tt> class. The decorator class, <tt>CoderDecorator</tt>, instead of simply
returning the coded string, displays the input and output strings' values and length.</p>

<p>The <tt>CoderDecorator</tt> class, like <tt>CoderImpl</tt>, implements the business method of the <tt>Coder</tt> interface,
<tt>codeString</tt>:</p>

<pre>@Decorator
public abstract class CoderDecorator implements Coder {

    @Inject
    @Delegate
    @Any
    Coder coder;

    public String codeString(String s, int tval) {
        int len = s.length();

        return "\"" + s + "\" becomes " + "\"" + coder.codeString(s, tval) 
                + "\", " + len + " characters in length";
    }
}</pre><p>The decorator's <tt>codeString</tt> method calls the delegate object's <tt>codeString</tt> method to perform the actual
encoding.</p>

<p>The <tt>decorators</tt> example includes the <tt>Logged</tt> interceptor binding and <tt>LoggedInterceptor</tt> class from the
<tt>billpayment</tt> example. For this example, the interceptor is set on the <tt>CoderBean.encodeString</tt> method
and the <tt>CoderImpl.codeString</tt> method. The interceptor code is unchanged; interceptors are usually reusable
for different applications.</p>

<p>Except for the interceptor annotations, the <tt>CoderBean</tt> and <tt>CoderImpl</tt> classes are identical
to the versions in the <tt>encoder</tt> example.</p>

<p>The <tt>beans.xml</tt> file specifies both the decorator and the interceptor:</p>

<pre>    &lt;decorators>
        &lt;class>decorators.CoderDecorator&lt;/class>
    &lt;/decorators>
    &lt;interceptors>
        &lt;class>decorators.LoggedInterceptor&lt;/class>
    &lt;/interceptors></pre>

<a name="gkpbk"></a><h3>Building, Packaging, Deploying, and Running the <tt>decorators</tt> Example</h3>
<p>You can build, package, deploy, and run the <tt>decorators</tt> application by using either
NetBeans IDE or the Ant tool.</p>



<a name="gkpag"></a><h4>To Build, Package, and Deploy the <tt>decorators</tt> Example Using NetBeans IDE</h4>
<ol>
<li><b>From the File menu, choose Open Project.</b></li>
<li><b>In the Open Project dialog, navigate to:</b><pre><tt></tt><i>tut-install</i><tt>/examples/cdi/</tt></pre></li>
<li><b>Select the <tt>decorators</tt> folder.</b></li>
<li><b>Select the Open as Main Project check box.</b></li>
<li><b>Click Open Project.</b></li>
<li><b>In the Projects tab, right-click the <tt>decorators</tt> project and select Deploy.</b></li></ol>

<a name="gkpaj"></a><h4>To Build, Package, and Deploy the <tt>decorators</tt> Example Using Ant</h4>
<ol>
<li><b>In a terminal window, go to:</b><pre><i>tut-install</i>/examples/cdi/decorators/</pre></li>
<li><b>Type the following command:</b><pre><tt><b>ant</b></tt></pre><p>This command calls the <tt>default</tt> target, which builds and packages the application into
a WAR file, <tt>decorators.war</tt>, located in the <tt>dist</tt> directory.</p></li>
<li><b>Type the following command:</b><pre><tt><b>ant deploy</b></tt></pre></li></ol>

<a name="gkpan"></a><h4>To Run the <tt>decorators</tt> Example</h4>
<ol>
<li><b>In a web browser, type the following URL:</b><pre>http://localhost:8080/decorators</pre><p>The Bill Payment Options page opens.</p></li>
<li><b>Type a string and the number of letters to shift by, then
click Encode.</b><p>The output from the decorator method appears in blue on the Result line.
For example, if you type <tt>Java</tt> and <tt>4</tt>, you would see the following:</p><pre>"Java" becomes "Neze", 4 characters in length</pre></li>
<li><b>Examine the server log output.</b><p>In NetBeans IDE, the output is visible in the GlassFish Server 3.1.1 output
window. Otherwise, view <tt></tt><i>domain-dir</i><tt>/logs/server.log</tt>.</p><p>The output from the interceptors appears:</p><pre>INFO: Entering method: encodeString in class decorators.CoderBean
INFO: Entering method: codeString in class decorators.CoderImpl</pre></li></ol>
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